Have you made creme fraiche before? It’s worth the extra effort, but you’ll have to remember to prepare the day before when you’re making your bechamel for the lasagna bolognese. In a non-reactive bowl, combine the heavy cream and buttermilk, cover with a clean kitchen cloth in a warm, draft-free place and let sit until thickened, but still a pourable consistency. This will take 12 to 16 hours. Once proper consistency, stir and refrigerate until ready to use. That’s it! Easy, and better than store purchased sour cream, but sour cream a suitable substitute. (Creme fraiche can be refrigerated for up to 1 week.)